1. Field of the Invention
This invention relates generally to a DC motor control circuit and is directed more particularly to a DC motor control circuit to be used in such devices as audio and video tape recorders.
2. Description of the Prior Art
In such devices as audio and video tape recorders, the rotational velocity of the DC motor has been maintained by a speed servo control circuit.
However, with a prior art speed servo control circuit, if the lock-in time of a servo to the DC motor is excessive at the start and the rotational velocity of the DC motor is significantly reduced or increased, the DC motor may become locked at a phantom lock-in point. Further, a prior art speed servo control is known which includes a starter circuit that directly supplies the DC motor with the power source voltage for a predetermined time in accordance with the operation of a power source switch or function switch. A servo loop is formed after the DC motor approaches a predetermined rotational velocity. With such a prior art control circuit, a DC motor suddenly stopped in its rotation, remains stalled until it is supplied with a start signal.